Supervisory control system



May 19, 1931. A. L. MOREAU 1,806,262

SUPERVISORY CONTROL SYSTEM Filed Aug. 9, 1927 6 Sheets-Sheet 1 M4 /25 0% M7 Z /3/ INVENTOR Awe/"7 L. fife/ecu! ATT'ORNEY May 19, 1931. A. L. MQREAU SUPERVISORY CONTROL SYSTEM Filed Aug. 9, 1927 6 Sheets-Sheet 2 v Alba/"f L. MOPGL1 TORNEY SUPERVI SORY CONTROL SYSTEM Filed Aug. 9, 1927 6 Sheets-Sheet 5 INVENTOR A/ber'f L. Noreau ATTORNEY y 1931. A. L. MOREAU -SUPERVI$ORY CONTROL SYSTEM 6 Sheets-Sheet 4 Filed Aug. 9, 1927 wmv INVENTOR Ame/"7 L. Moreau ATTORNEY May 19, 1931. A. 1.. MOREAU fi fi SUPERVI SORY CONTROL SYSTEM Filed Aug. 9. i927 6 Sheets-Sheet 5 INVENTOR A/b er? L. Noreau ATTRNEY 19, 1931.. A. l... MOREAU SUPERVISORY CONTROL SYSTEM Filed Aug. 9. 1 2 6 Sheets-Sheet 6 I ATTORNEY Patented May 19, 1931 UNITED STATESPATENT' OFFICE ALIBEIET IJ. MOREAU, OF VVILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA surnavrsonr ooN'rBoL sYsrEm' Application filed August 9, 1927. Serial No. 211,682.

My invention relates to signallin systems and, more particularly, to the se ectlve control and supervision of remotely disposed ap aratus units in a power system,

11 object 0f my invention is to provide means for synchronously operating chains of relays to select apparatus units for operation and supervision.

Another object of my invention is to provide means for identifying the selecting position of the synchronously operated chains of relays at each position.

Anotherobjeet of my invention is to provide means for operating a plurality of groups of synchronous selecting relays at each station in synchronism.

Another object of my invention is to provide means for preventing operation of a synchronous relay system comprising a plurality of groups of relays at each station, when relays in non-associated groups energize simultaneously.

Another object of my invention is to provide means for operating chains of relays in synchronism by means of code combinations of impulses.

Another object of my vide means for restorm invention is to prothe chains of relays to their normal position should they fall out of step.

Another object of my invention is to provide means in a synchronous system for transmitting code combinations of impulses to operate selected apparatus units.

Another object of my invention is to provide means for remotely connecting two synchronous power systems to each other while in proper phase and synchronism, employing therefor operation control in a synchronous relay system.

Another object of my invention is to pro vide means for controlling the operation of a driving circuit which operates two chains of relays in synchronism by the correct receipt 0 supervisory 'si Another ob3ect of my invention is to provide means for controlling the impulses over a drive circuit by supervisory signals.

Another object of my invention is to pro vide means for operating relays at two remotely disposed stations in synchronism by means including two independent circuits each operating from an individual station controlling each other.

Another object of my invention is to provide means for operating a selected apparatus unit with a single impulse in a synchronous relay system employing code combination of impulses on all other points for operating selected apparatus units.

There are other objects of my invention, which together with the foregoing will appear in the specification which follows:

A major factor in the development of a signalling system for selectively controllin and supervising large units of electrica power systems resides in the accuracy of the selective operation which can be obtained. While in all other signalling system such as telegraphy and telephony, a reasonable percentage of error in the selection is permissible, supervisory control systems on the other hand, must operate with infallible accuracy. Failing to make an accurate and correct selection, it is essential that the s stem make no selection and that the dispatc er be apprised immediately of the failure in the system so that correction can be made and the system be in operative condition again as soon as possible.

Another characteristic of supervisory control systems which distinguishes them radicall from other signalling systems, resides in t e fact that it is called upon to give comparatively little service as compared with f soon as it is called upon to perform any of service, either to control or to supervlse or both. I

Supervisory control systems have already been developed in which chains of selecting apparatus'remotel disposed from each other have been operate in synchronism by means of chains of relays which counted'the impulses, these latter relays energizin lock-- mg up, and remaining lockeduntil t e completing of the cycle of operation. It is desirable, however, to maintain a minimum load on the batteries at-the stations and this can ,best be accomplished by maintainin as few relays energized at one time as possible. In

. the present arrangement, provision is made for sequentially deenergizing as well as energizing the counting relays so that a minimum of these are maintained energized at any one time and the load on the battery considerably reduced.

It is also highly desirable to operate selecticative ing a paratus at as high a speed as possible in or er that signalling impulses in of a chan e of an apparatus unit are received possible.

at the o so as soon after an operation .as is At the same time the speed of selector operation must not be such as to prevent or cause a loss of a supervisor signal due to the signal not being receive before the selecting apparatus stepson to the succeeding point.

visory signal momentarily take control of i the selecting apparatus operation, preventing the operation of the selecting apparatus until the supervisory signal has been corrected. While synchronous operation of selecting apparatus has been found to be the most practical method of selection for remotely controllin and supervising circuit breakers or other el ctrical units, there is a possibility, in cases where the systems are subjected to severe inductive surges, such as that induced by adjoining power systems, of false operations'sincethe units in such a s stem are directly connected to thev si Surges impressed on a signal inggline ma therefore cause a false operation of the unit which at the time of the surge is associated with the si alling-line. In order to overcome this ifliculty arrangements, are pro-v vided whereby, after the unit has been selooted by a synchronous selecting system, a code combination of impulses is transmitted over the signalling linefor finally operating tems should be instantly connected.

It would not be practical, therefore, to

transmit a code combmation of impulses for connectin' the system. By the time such a code has n correctly received the selection of the succeeding point.

his is overcome in the pres ent invention by-arranging to have the superread a1 ing line.

be repeats may again be out.of synchronism.- Where remote systems are to be connected when in phase and in sg'nchronism, it is desirable to connect them y a single impulse. At the same time, provision must be made against the operation of the unit connecting these systems, by a surge coming, as this unit is associated with the signalling line. This is provided for in the present case by a simple and expeditious arrangement for connecting the two remote systems depending on their relative phase and synchronism by the more At the same time should the unit be stepped over during the selection of other points "a single surge 1mpulse will not operate this unit. y this arrangement a single impulse operates a selected unit which at the same time is protected from surge efiect of any ower system.

In order to prevent false se ecting o ration, each selectin point is identified y a check circuit whic must becom leted and causes the oeration of predetermined relays before the r selecting point is completed and'controland supervision operations can be performed. Should the check circuit fa l to operate, provision is 'made for automatically conditionin the apparatus at the remote station to e reset while' at the same time holding the final operating circuit open. At the same time a warning slgnal is transmitted to the dispatcher at the ofice end that the apparatus .is out of synchronism and by ogerating a .reset key. False selections are t us prevented.

In order to prevent bulkiness of the system, where a lar e number of units are to be 0 ertofbe'reset. The dispatcher can then and can resetthe a aated, the se ecting apparatus is. divided into f groups usually ten in each grou 'lhe first ten selectin points are select m sequence andthen t a common operation apparatus shown in the Figures 8 and 4 are switched. over to select the next ten, and so on. In. the switching operation, it may happen that the battery at one of the stations momentarily fails in which'case the selectionwill d for the first ten while at the remote station where the battery did not fall,

selection would be made for-the second ten.

Since-the selecting operations' are arranged to be. re

ted for each group,'no provision is usual made for detecting the false or non-sync ronous condition due to operations 1 .in incorrect groups. By providing a dummy point in the first group, in the present case, this difliculty is overcome, since the dummy point is not like any other selecting point and does not reappear in the other grou s.

If a station battery fails at any point in t e selection so that the first group is reoperated while another group is operated at the remote station, the dummy point will be first selected and since it will not check with any. of the other points in the other groups, selection will be stopped in a manner equivalent to that described above in connection with a non-synchronous condition. y

Referring now to the drawings, Figures 1 to 3 are diagrams of the circuits and apparatus at the dispatchers oflice, and

Figures 4 to 6 are diagrams of the circuits and apparatus at the substation.

Fig. 7 is a diagram of the circuit showing the relation between two succeeding groups of selecting relays.

Referring more particularly to Fig. 1, the lamp 101 is a flicker lamp which periodically goes on and oif to advise the dispatcher when the selecting apparatus is started into operation from its normal non-o crating condition so that he will watch or supervisory signals. The key102 is the alarm key which the dispatcher may operate to stop the flickering operation of the flicker lamp 101 after the selecting apparatus has returned to its normal non-operating condition. Lamp 103 is a stop lamp individual to a selecting point and is characteristic of equivalent lamps at each selecting point. This lampis illuminated as the selecting apparatusreaches the position individual thereto and the dispatcher is thereby informed of the position of the selecting apparatus. .The key 104, 105 is the stop key of the type which remains in the poing point. By operating the stop'key, to the open position shown, the selecting apparatus can be brought to a stop at the position individual thereto or, if the stop key is left in its unoperated position, the selecting apparatus will continue and step over this selecting point to the succeeding point. This key is I shown in the operated or open position. Key 112, 113 is an operate twist key individual to a selecting position, there, being an equivalent one for each of the other selecting positions. By operating thesekeys, the desired kind-of control operation on the individual unit associated with that particular selecting point at the remote station can be performed.

Thus, with this key in one position, a circuit is prepared for transmitting impulses for operating the circuit breaker to its closed position, or with the key in its alternate position, a circuit is prepared for transmitting impulses for operating the circuit breaker to its open position.

The lamps 114 to 117 are individual to each selecting point. The lamp 114 when illuminated indicates that the twist key 112, 113 is in disagreement with the condition of the apparatus unit. That i s, if the twist key has been movedtoitsclosed position, to close the circuit breaker and thereafter for mine reason the circuit breaker has autosition set and is also individual to each selectmatically tripped, the twist key would ordinaril be in positlon indicating that the circuit reaker is closed whereas actually it is tripped. Under such circumstances, the lamp 114 is illuminated to indicate that the twist key and the circuit breaker are in disagree ment. The lamp 116 is illuminated to indicate that the circuit breaker is in its tripped position, lamp 115 is illuminated to indicate that the circuit breaker is in its closed position, and lamp 117 is illuminated to indicate the position of the selecting apparatus. This lamp illuminates when the selecting apparatus has reached the selecting point individual to this lamp. The keys 118 to 121 are the trip and stop keys individual to the second point. Similarly, the lamps 124 to 127 and keys 128 to 133 are individual to the succeeding selecting point.

The key 134 is a reset key, which as will be described hereinafter, functions to cause the selecting apparatus to be reset to its normal non-operating position at any point in the operation. The lamp 135 flickers to indicate that the selecting apparatus is in synchronous operation. Lamp 136 illuminates when the selecting apparatus starts into operation and indicates that the set is runmng. If lamp 136 is illuminated and 135 does not flicker, the dispatcher is warned that there is trouble.

The key 137 is a start key. In order to start the chain into operation, the key 137 must first be closed as will be described hereinafter. Lamp 138 is a normal white lamp indicating that the apparatus is in normal non-operating condition.

The key 139 is the master control key. When the proper unit has been reached and the operate key has been moved to the proper operate position, the master key is closed to impress the necessary energy upon the line for performing the desired operation on the unit. The relay 141 is a supervisory receiving relay individual to each selecting position and operates in accordance with t e condition of its individual apparatus units for operating the signalling lamps.

The synchroscope 145 is operated at its individual position in the selecting system by im ulses received from the remote substation to indicate when two individual power circuits are in phase and in synchronism for remote synchronizing. The relay 153 functions to permit the apparatus to be restored to its normal conditions even though the final operating control impulse is about to be transmitted for performinga desired operation. This relay also functions to complete an energizing circuit for relay 149 which connects the synchroscope into the systemat the completion of the operation control code, when 9. single impulse will operate the remote unit.

Referring to Fig. 2, the relays 210 to 219 are indicatrve of the selecting relays indi- ""jeriodicaly e vidual to each point. Although only ten such selecting rela s are shown in the'illustration, it will be und erstood that any number of selecting relays. may be employed in my sys- 5 tem. Individual to each of these selecting relays is a'switchover relay 200 to 209. These relays are arran ed to energize following the operation of their individual selecting'relay for transferring the operating impulse 'from the drive rela to the succeeding selecting relay. It will lie noted that each selectin re- .lay is locked over the back contact of individual switchover switchover relay ener ms, the selectin relay is deenergized. imilarly,-each switchover relay is in turn held energized over the back contact of the succeeding switchover relay so that upon the'energization of thesucceeding switchover relay the preceding switchover relay is deenergized. In this 'manner the relays are all 'normallymaim tained deenergized and only two relays, a selecting and a switchover relay are energized at any one time.

Referring to Fig. 3, relay 300 is a supervisory receivin relay energized in response to the receipt 0 a supervisory signal indicatmg a closed condition of the apparatus unit and repeats the impulse to the proper indi vidual supervisory signalling relay 141. Similarly, the relay 301 is the common trip relay energized in response to the receipt of a supervisory trip signal indicating thatthe circuit breaker individual to the particular point is tripped and transfers the impulse to the individual supervisory recelving relay such. as relay 141. Relay 312 cooperates with the relays 300 and 301 to control the drive circuit and prevent further 40 operation thereof until the supervisory impulse has been fully received and the local 7 operation ance with t e operation of the remote a paratus unit. This will be more apparent em the detailed description which is to follow.

The rela 313, when ener 'zed, in turn, controls the rive circuit un er control .of the I relays 300, 312 and 318and of the stop -key.

he relay 318 in turnis directly controlled eofrom the stop key. With the stop key indivldual to each point in itsoperate position, the relay 318 will not be energized. If the stop key is left in its non-0' erjate positron, a circuit will be completed lay 318 which, in turn, completes 1ng circuitfo'r the relay 313 which, u on energizmg, opens the circuit forthe riving relay 314 at armature 346. These op 0 operations which follow hereinafter;

The relay 314 is the driving relay which energizes as the relay 313 energizes and energizes to transfer impulses to the selecting relays. Upon each successive energization of the relay 314, an impulse is 'tlme the relay 314 energizes,

relay so that when its,

relay such as i holdmglrelay 333. starts t operation of each so roperly performed in accord for the 'rean energizthe relay 333 which upon'ener erations are described in detail in the description of transferred to the selectinlg rela through contacts of the switchover re a s w ch, as pointg ed out above,-determine w '01; of the select,- I ing relays is to be-energized. Thus, the it com letes an energizing circuit for thefirst selecting relay and the second time relay 314 energizes,a circuit is completed through the-switchover relay to energize the second selecting relay and so on. The polarity of current for the drive rela 314 is determined by the ener 'zation or eenergization of the relay 315 w ich, in turn, is controlled from the switchover relays in a manner to be described in detail hereinafter. During the first four operations the relay 315 is maintained deenergized and energ is transmitted from the negative side of attery at the ofice to the relay 314, but after the energization of the fourth selecting relay, the relay 315 is ener'ed and the polarity of current throu hte relay 314 is reversed in a manner which is described in detail hereinafter. f I Y The relay 333 is a normalhole relay energized over the back contact of armature 362in series with a normal holding rela at the remote station. Therelay 322 whic controls the energizing circuit for the relay 333 is energized by closing the start key and opens the energi'zmfi circuit for thenormal nergization of relay 322 aFparatus into operation.

e selecting The relay 319 is nergizedfollowing the ectin relay at the office and substationfor indicating thatthe selecting relays are in chronism. If the relay 319 does not energize following the energization of a selectin relay, this indicates a nonsynchronous con 'tion and will cause operations of, relays forrestorin the ap ratus to normal in amanner to be 7 escribe in detail hereinafter. Relay 320 energizes following the energization o the synchron'izin' check relay 319 to in turn energize relay 32 The energization of the rela 321-transfers the control and supervisory hne to their final operating position and at the same time. opens the circuit of the synchronizing relay 319.

The relay 331 energizes if two selecting relays energizesimultaneously at the ethos or if any other than the correct selectin relay has energized, and functions to comp ete an energizin circuit for. the rela 334 which controls-the energizing circuit. or the relay 322 and causes the relay to lleenergize,lthere-. by. preparing theoriginal holding circuit, for ation would restorethe apparatus to normal by removing ground from all of the locking circuits at armature 337 in amanner to be described in detail hereinafter. The relay 331 also ener gizes at the end of the energization of the last selecting relay in the system to restore the ap paratus to normal. Relays 330 and 331 cooperate with the relays e32, 329 and 384 for perm no I forming the restoring operation during either a non-synchronous condition or the final operation of the last selecting relay. Relays 324, 325 and 326 are energized when the selecting apparatus starts into operation for operating flicker lamp 101.

In orner that a large number of units may be operated it is advisable to divide the system into groups of small numbers as for example ten in each group. Arrangements are provided for switching over to the succeeding group of ten at the end of each group. During the switching operation, it may happen that the battery at one end is momentarily removed due to some accidental cause and instead of switching on to the succeeding group, the first group of selecting ap aratus starts all over again, while the secon group is operating at the remote end. In order to prevent this a dummy selecting point is pro vided at the beginning of the first group which is different from the first point of the succeeding group, so that the check circuit does not agree. This is accomplished by means of relays 316, 317 and 327 which comprise the normal first selected point although not an actual selecting point and does not com-- plete a check circuit. Since the check circuit is not completed the selecting action is stopped and the control and supervisory lines 335 and 362 are opened, thus preventing any false operation of the apparatus units.

Following a selection of an apparatus unit, instead of transmitting a single impulse to operate the unit, a code combination of impulses are'transmitted. This code is called an operation control code. The relay 303 energizes in response to the operation of a closing key for determining the code which is to be transmitted for a closing operation and the relay 305 energizes to determine the code which is to be transmitted for performmg a trip operation. The relay 306 is part of this code transmitter and is periodically energized under control of an impulse transmitted from the remote station and under control of the relay308, the circuit being opened from the remote end as will be described in detail hereinafter. Relays 307 to 315 are energized in sequence in response to the transmission of these code impulses in a manner to be described in detail hereinafter and the relay 302 is'maintained energizedduring the transmission of these codes until the end of the operation, relay 302 indicating when the complete code has been transmitted. Referring now more particularly to Fig. 4, relay 421 is the normal holding relay energized over the line in series w'ith'the relay 333.

The relay 421 when deenergized starts the apparatus into operation and when energized opens the locking circuits of certain relays to restore the apparatus to normal.

Relay 414 is the driving relay which is periodically energized to transfer energizing impulses to selecting relays. The polarity of the current on the relay 414 is determined by the relay 415 which is maintained deenergized during the operation of the first four selecting relays and energized during the operation of the second group of four selecting relays. Upon each energization of a selecting relay, the relay 412, which is a check relay, is energized and determines thereby whether the correct selecting relay has energized. Upon the energization of the check relay 412, the relay 411 energizes which in turn completes an energizing circuit for the relay 410. The relay 410 switches the control and supervisory line through their final operating position,-'these circuits being normally maintained in non-operating conditions'during the normal operation. Upon the operation of the relay 410, indicating that the proper switching operation has been performed, relay 413 energizes to open the energizing circuit for the check relay 412. In order to prevent an inaccurate operation, following the switching from one to another chain of relays, the relays 416, 417 and 425 function as an extra or dummy selecting point in a manner which has already been described briefly above and will be described in more detail hereinafter. Relay 419 is periodically energized from the contacts of the driving relay and being a slow release relay,-remains energized during the operat ing period between the energization of the drive relay. Upo n deenergizatlon of the drive relay for longer than the normal period, this relay deenergizes and starts the restor ingapparatus into operation for restoring the apparatus to normal. Relays 418 and 420 cooperate with relay 419 for restoring the apparatus to normal.

Relays 422 to 424 operate in response to the operation of two selecting relays orany selecting relay other than the correct selecting relay for restoring the apparatus to normal. If an automatic operation of a unit takes place during the period while the apparatus is in operation, relays 426 and 427 operate to store the supervisory impulse for later transmission after the selecting apparatus has gone through its 0 cle of operations and restarted. Relay 408 unctions to switch the supervisory and drive line at -the end of a certain number of selecting operatlons so as to reverse the functions of these two lines.

Relay 400 receives the periodic imfpulsing for transmitting the code operations or operation control, the circuit for this relay being controlled from the remote end. Relays 401 to 405 inclusive are sequentially energized by the code impulses, and relays 406 and 407 determine the operation to be performed, that is, a trip or a closed operation. v

Referring now to Fig. 5, relays 510 to 519 are the individual selecting relays and the reits are shown, 617 and 620. It is understood, of

course, that these are merely illustrative for any number of circuit breakers, one for each of the selecting oints. Relays 600 601, and 611 to 614 are in 'vidual to the circuit breaker 617 and the operating ma nets 615 and 616 erform the operations on t e circuit breaker.

he circuit breakers, it will be understood, may be automaticall operated; the apparatus associated with the other circuit breaker 620 is illustrative of an arrangement whereby remote'synchronization can be obtained with.

this system in which synchroscope readings are transmitted over the normal control and supervisory line. A code of impulses for performing the control operation is previously transmitted in the case of remote synchronization for setting up the proper condition so that when the synchronous condition is reached, only a sin le impulse is necessary to perform the desired operatiom This is accomplished by the relays 602', .603, and 604 to 606 in a manner WhlOll will be described in detail hereinafter. The relays 607 and 608 are the intermediate relays for closing the circuits to the trip or closed solenoids 609 and 610 which in turn close circuits to the operating magnets 618 and 619 of the circuit breaker 620.

Having now described the apparatus'employed in my system, I will now describe the operation which takes place in selectively o erating an apparatus unit in order to rev1de a better understanding of the invention.

Although I have shown a (plurality of batteries both at the ofiice en of my s stem (Figs."1-3) and at the substation end Figs. 4-6) it is obvious that'only one battery, such as 335, at the oflice and a similar battery 429 at the substation will benecessary. The conductor Cm, connecting the batteries 335 and 421 to batter 429, is the'common return conductor of the system.

With the system at rest, there is a normal holdin circuit completed from the 'positive side 0% battery 335, Fig. 3, conductor 336, through the winding 0 the rela 333, the back contact and armature 362, t e control line 335, the armature 428 and. its back con= tact, and through the windin of the relay and ground. t. a result of the energizat on of the "relay 333, an energizin; circuit is completed for the normal Sign :1 lamp 138. from throuh battery at the ofiee, Fig. 1 a rough the 1.1% ment of the lamp 138, conductor 153 and the front contact and armature 337 to oundg. The illumination of the lamp 138 indicates that the s stem is in its normal non-operating condition with the apparatus in preparation for an operation. A further result Atthe substation, as a result of the energi- V zation of relay 421 an ,energizin circuit is completed for the relay 419 from t e negative 'side of the battery 429, Fig.4, to the winding of the relay 419, the front contact and armature 430, to the positive sideofthe battery 429, over conductor 431. The energization of the relay 419, prepares an energizing circuit for the rela 420 which functions in a manner to be described in more detail hereinafter to restore the apparatus to normal should the selecting-relays at the office and substation fall out of step. A further result of the ener 'zation of the rela 421 is to'prepare a loc ing circuit over t e armature 432 in a manner to be described in detail hereinafter. It will be assumed for pur osesof illustration that the dispatcher desires to operate the circuit breaker 617 from its tripped toits closed position; In order to perform this operation, it is first necessary for the dispatcher to start the apparatus into operation y closing the start ey, operating the stop key individual to the unit which he desires to operate in order to bring the selectin apparatus to a stop at the-position individual to the. circuit breaker 617, operate the individual operate key and finally when the unit has been reached operate the master control keyl to. perform the desired 0 eration. It wi be assumed therefore that t e dispatcher momentarily closes the start key 137 and itscontacts eng A circuit is thereupon completed from ground toba'ttery armature 340, Fig. 3, and its back contact, th rela 322, the back contact and armature 341, con uctor 342, the contacts of the start key 137, conductor 159, and the back contact and armature 339 to ground. A multiple circuit is completed for the lamp 136 overthe contacts of key 137. This lamp illuminates to indicate that the system is in operation.

Asa result of the energi'zation of relay 322 over the circuit just traced, the original holding circuit for the relays 333 at the ofice and 421 at the substation is opened at armature 362 which has now moved from angagement with its back contact to engagement with its front contact. A further re-- sult of theenergization of relay 322 is to prepare an operate circuit for the control line over armature 362 and its front contact and for the supervisory line over the armaits rough the winding of thefor the normal lamp 138 is opened at the armature 337 which has moved from engagement with its front contact to engagement with its back contact. At the same time an energizing circuit by-passing the start key 137 is completed for the green lamp 136 which indicates that the set is in operation from ground-through battery through the filament of the green lamp 136 over the conductor 342 and the back contact and armature 337 to ground. A further result of the deenergization of relay 333 is to complete a circuit for the relay 322 by-passing the start key from ground through battery, the armature 340 and its back contact through the winding of the relay 322, the back contact and armature 341 and the back contact and armature 337 to ground. These circuits for relay 322 and lamp 136 are thus maintained complete, even after the start key has been released to itsiiormal open position.

A further result of the deenergization of relay 333 is to complete an obvious energizing circuit for relay 326. Relay 326 locks over the contacts of ke 102 and also completes a vibrating circuit for relays 324 and 325 which sequentially open each others circuit and cause the lamp 101 to flicker.- The dispatcher is then apprised that the system has started into operation. 7

At the substation upon deenergization of the normal holding relay 421 normally energized' over the holding circuit, an energizing circuit is completed for the relay 40.9 from ground over the armature 432 and its back contact through the winding of the relay 409, the back contact and armature 433, and battery to ground. As a result of the energization of relay 409,11, circuit is prepared for the control line over armature 428 and its front contact, but this circuit is not completed at this time for reasons that will be described hereinafter.

A further result of the energization of relay 409 is to complete a drive circuit at armature 431 for energization of the drive relay 414 at the substation and relay 314 at the office. This circuit is completed from ground 7 at the office through battery over the back contact and armature 345, the Winding of the drive relay 314, the back contact and armature 346, the conductor 347, armature 348 and its back contact, the front contact and armature 349, armature 350 and its back contact, the drive line 351, the back contact and armature 434, at the substation, Fig. 4, armature 435 and its back contact, armature 431 and its front contact, through thewinding of the reljay414 and armature 444 and its back contact to ground.

As a result of the energization of the relay 314 at the completedfor the relay 316 from ground through battery, the winding of the relay 316, the armature 347 and its back contact, and the office, an energizing circuit is front contact and armature 348 to ground. The energization of the relay 316 completes a locking circuit for itself from ground through battery, the winding of the relay 316, front contact and armature 343, back contact and armature 351, conductor 355, back contact and armature 222, conductor 342, to the back contact and armature 337 to ground. A further result of the energization of the relay 316 is to complete an energizing circuit from ground over the armature 353 and its front contact, through the winding of the relay 318, conductor 354 to negative batteryand ground.

The energization of the relay 318 completes an energizing circuit for the relay 313 from ground over the armature 353 and its front contact, the front contact and armature 355, the back contact and armature 356 through the Winding of the relay 313, the back contact and armature 357 and over conductor 354 to battery and ground. As a result of the energization of the relay 313, the orig inal energizing circuit for; the drive relay 314 is opened at armature 346! During this period while the drive line is closed and the operations just described were being performed at the oflice, the drive relay 414 is energized at the substation in the manner described above. As a result of the energization of the relay 414, an energizing circuit by-passing the circuit traced above over the front contact of tlie normal holding relay 421, is completed for the relay 419 from ground over the armature 436 and its front contact, through the winding of the relay 419 to the negative side of the battery 429. A further result of the energization of the relay 414 is to complete an energizing circuit for the relay 416 from ground over the armature 437 and its front contact, armature 438 and its back contact, back contact and armature 441 and through the windin of the relay 416 to battery and ground. is a result ofthe energization of relay 416, alocking circuit is completed for itself from ground through battery, the Winding of relay 416, front contact and armature 443, the b ack contact and armature 442, conductor 439, the back contact and armature 520, conductor 521, and the back contact and armature 432 to ground.

When the drive line is now opened at the ofiice as a result of the energization of relay 313 described above, the drive relays 314 at the ofiice and 414 at the substation are deenergized. As a result of the deenergization of relay 314 at the oifice, an energizing circuit is completed for the relay 327 from ground through battery, the winding of the relay 327, the front contact and armature 359, and to the back contact and armature 348 to ground. The relay 327 is energlzed over the circuit traced above, and completes a locki g circuit for itself from ground mg clrcuit for' the relay 316 at armature 351.

Relay 316 is deenergized which, in turn,

10 {pens the energizing circuit for the relay 318.

pm deenerglzation of relay 318, the energizin circuit for relay 313 which was complete over armature 355 is opened. As a result of the 1denergization of the relay 313, the original energizmg circuit for the drive pleted. v

-Duringthis period while the drive line is open, upon deenergization of the relay 414, at the substation, an energizing circuit is completed for the rela through'battery throug the winding of the relay 417, the front contact and armature 440' and the back, contact and armature 437 to ground. As a result of .the energization of the relay 417, a locking circuit is completed therefor from ground through batter winding ofthe relay 417, front contact an armature 442, conductor 439, back contact and armature 520, conductor 521, and the 30 back contact, and armature 432 to ground.

A further result of the energizationcf the relay 417 is to open the lockin circuit for the relay 416 at armature 442. fie relay 416 is, as a result, deener ed. Y A further result 0 the energization of the relay 417 isto complete an energizing circuit for the relay 425 from ground to battery, winding of the relay 425, the front contact and armature 440, and over the back contact and armature 432 to ground. e energization, of the relay 425 completes a locking circuit for itself from ground through battery winding of the relay 425, front contact and armature 454 to ground over the back contact'and armature 432.;

It will be noted that the first drive impulse did not energize a selecting rela as each succeedin'g drive impulse does. e purfio se of this is to increase the reliability oft e system, especially when a large number of selectmg points are emplo ed. a! The relays 316, 317 an 327 at the ofiice and the relays 416, 417 and 425 at the substation constitute dummy points. If there should be a momentary fai ure of battery when switchilg fromone group to the next, the first ten s acting relays may be reoperated while the mcond group arebeing'operated at the ether station. Since under certain circumstances it may be desirable ta employ the same check circuit repeated in the second-group, such a condition would ordinarily not be detected. By providing a dummy intsuch as described above, the check circuit will fail on p w the first point and the apparetuarestored'if relay .314 over the armature 346 is again comv 417 from "ground,

. and to the third scription to follow, as

a condition such as described above occurred.

Upon the deenergization of the relay 313, a second'drive impulse for the relay 314 at the office and the relay 414 at the substation, is transmitted over the circuit which has already been traced. As a result of the second energization of the relay 314 at the oflice, an

relay 210, back contact and armature 221', the

back contact and armature 225, conductor 342 and the back contact and armature 337- to ground.

At the substation, upon the energization of the relay 414 for the second time, an ener ing circuitis completed for the first selecting re ay 510 from ground through battery, to the winding of the relay 510, a conductor 525, armature 456 and its front contact, the back contact and armature 438 and the front con- I tact and armature 437, to sult of the energization 0 locking circuit is completed therefor, from ground through battery, to the windin of the relay 510, the first contactof the re ay, the back contact and armature 526, back contact and armature 527, conductor 521, and the back contact and armature 432 to ground.

7 Upon the energization of the first selecting relay 210 at the ofice and 510 at the substation, a check circuit is completed depending ground. As a reon the energization of equivalent selecting relays at the ofiice and at the substation. In

the present instance, this circuit is completed from ground through battery, third contact of the selecting relay 210, the back contact and armature 358, through the winding of the check relay 319 at the oflice, the fourth contact of the selecting relay 210, conductor 261,

back contact and armature 361, the front contact and armature344, armature 373 and its back contact over the supervisory line 362, back contact and armature 445, armature 446 and its back contact, armature 447 and its front contact tact the conductor 449, to the fourth contact ofthe selecting relay 510, conductor 450 to the winding of the check relay 412, the armature 451 and its back contact, conductor 452 und. Ihe check circuit just traced, it will e noted, is completed from the negative side line, to

I mtive side of battery, at the substation.

s will be ilo'inted out in the de 0 pair of e uivalent selecting relays in a group are provi ed with individual check circuits so that as each secontact of the relay 510 to the rela 510 a armature 448 and its back conselecting relay at the substation, had been energized simultaneously, the check circuit would have been com leted from ground to ground including no battery. Under other circumstances, no circuit is completed as, for example, where the selecting relay at the oflice prepares a check circuit through the control 7 contact and .tery to therelay 411, 7 the armature 467 and its back contact, windarmature line and the selecting relay at the substation prepares a check circuit through the supervisory line. Thus the circuit can be comleted only when'the equivalent selecting reays in the group are energized together at the ofice and substation.

In the present case, it was assumed that the correct associated selecting relays were energized and as a result the proper check circuit was completed for energizing the check relay 319 at the oflice and 412 at the substation. As a. result of the energization of the check relay 319, an energizing circuit is completed for the relay 320 from ground over the armature 366 and its front contact, through the winding of the relay 320 and batglround. As a result of the energization of t e -relay 320, a locking circuit is completed for this relay from round to battery, through the winding of 516 relay 320, the front contact and armature 37 5, and through the front/contact and armature 348 to ground.

A further result of the energization of the relay 320 is to com for the relay 321 rom lete an energizing circuit ground through batthe winding of the relay 321, the front armature 37.8, and the front contact and armature 348 to ground. The energization of the relay 321 functions to open the check circuit just traced for the rela 319 at armature 361 and to switch the control and supervisory circuits through to the final operating oint, thereby preparing the selected circuit or o eration.

At the su station the energization of the relay 412 completes an energizing circuit for from ground through battery,

of the relay 411, the front contact and ing 468, conductor 470 to the fifth contact of the first selecting relay 510 to ground.

' from As a result of the energization of the relay 411, a locking circuit is prepared therefor oundlthroughbattery, the armature 467 an its back contact, thr0ugh the winding I of the relay411, front contact and arntrature contact and armature 436 to this time or the rel 471 and through the front contact and armature 436 to ground.

A further result of the energization of relay 411 is to complete an energizing circuit for the relay 410 from round to battery,- t-hrough the winding of t e relay 410, to the front contact and armature 455, and the front round. The energization of relay 410 opens t e energizing circuit for the check relay 412 at armature 448, thereby deenergizing the rela 412. A further result of the energization o the relay 410 is to complete the control and supervisory operating circuits.

Before describing, however, the operations which take place on individual operate oints, the operations which are performed w ereb the succeeding selecting points are reache will now be described. It will be noted that during drive relay 314 at the ofiice and 414 at the substation remained energized. An energizing circuit for the relay 313, it will be recalled, was completed over'the armature 32(51 of the relay 318, which, in turn, is energiz over a circuit includinglthe armature 353 of the relay 316. The relay 316, however cannot be energized this time by reason 0 the fact that the relay 317 is energized, opening the energizing circuit for the relay 316 at armature 347. j 4

A multi le circuit however, is prepared at eiy 318 over the armature contacts of the relay 321, and the contacts of the stop key. Ass 'ng for the purposes of illustration that the stop key individual to the first selecting relay was not operated. to its open position but remains in the position shown, an energizing circuit is now com leted for the relay 318 from ground throng "battery, shown in Fi 2, over the conductor 354, the winding of t e relay 318, armature 379 the operations thus far traced, the

and its front contact, conductor 390, stop key,

conductor 160, and through the fifth contact of the first selecting relay to ground. This circuit, it will be note is completed key is in its closed or normal only if thestop position and is com leted immediately following the closing 0 the selectin relaycontacts and energization of the re ay 321 followin the check 0 ration which has been descri ed in detail a ve. As a result of the energization of relay'318, a locking circuit is com leted for this relay from ground throu better over the conductor 354 and the winding 0 the relay 318, front contact and armature 391, over the conductor 390 and over the circuit back contact and'arinature 35.7, to battery over the conductor 35.4 as stated above. Re-

lay 313 is energized'over this circuit and it drive relay 314, an energizing circuit is com pleted for the first switchover rela 200 from ground through battery, the win ing of the switchover relay 200 over the conductor 268, the second contact of the selector relay 210 through conductor 269 and the back contact and armature 348 to ground. The switch-y over relay 200 is energized over the circuit traced above and-completes a locking circuit for itself from ground to battery through the winding of the relay 200, front contact and armature 221, and the back contact and armature 225, conductor 342, through the back contact and armature 337 to ground. The energization of the relay 200 also switches the energizing circuit repeated by the drive relay 314 from its associated selecting relay to the succeeding selecting upon the next energization of'the drive relay, the relay 211 instead of the relay 210 will be energized. A furtherresult of the energization of the switchover relay 200 is to open the locking circuit for the selecting relay 210 at armature221 and the locking circuit of relay 327 at armatur 222.

t the substation, he deenergization of the relay 414 completes a locking circuit for the switchover relay 500 from ground over armature 437 and its back contact, conductor 469, through the second contact oi the selectin relay 510, energized, and through the win ing of the relay 500 to battery and ground. As a result of the energization of the relay 500 .a locking circuit is completed for itself from ground through. battery, through the winding of the relay 500, frontcontact and armature 526, the back contact and armature 527, conductor'521, to ground over the back conta t 3 armature 432. A further result lookng for relay 510, which, it. be recalled,was completed over the back co'ntactof armature 526, which has now ovedfro m its back-contact to its rroht "contact, A further ,resultoi energization of relay is to transfer the ener rug circuit previously traced for the selecting relay 510 the selecting relay 211, so that from the drive relay 414, three the switch.

of the selecting relay 210 is denergized. v The deenergization of the relay 318 opens] the energizing circuit for the relay 313, which,

upon deenergization again closes the, drive circuit for the relay 314' at the oflice, and 414 at the substation, at armature 346 and its back contact.

Drive relays 314 and 414, are now reenergized over the circuit previously traced, and

armature 348 and its front contact, the front contact and armature 220, and through the winding of the selecting relay 211 to battery and ground; Atthe substation, the energization of the drive relay 414 completes an energizing circuit for the second selecting relay over a circuit from ground over armature 437 and its front contact, armature 438 and its back contact, the front contact and armature 535 and through the winding of the sec ond selecting relay 511 to battery and ground.

As a result of the energization of theselecting relay 211 at the ofice, a locking circuit is, completed for itself from ground through battery, through the winding of the selecting relay 211 through its first contact, the back contact and armature 224 and the back contact and armature 228, conductor 342, and the back contact and armature 337 to ground. At the substation, as a result of the energizetion of the selecting relay 511, a locking circuit 'is completed for itself, from ground throu h battery, the winding. of the selecting re ay 511, its first contact, the back contact and armature 536, back contact and.

i e v v looting relays at theofice and substation.

; otthe energization' of relay 500 is to open the A tend completed from ground at the ofice' through the third contact of the second selecting relay 211, the back contact and armature 358, through the winding of the 319,- over to fourth contact of the check relaycheck relay 211, conductor 261-, the back contact and arms ture 331, the frontcontact and armature armature 373 and its hack contact, through the supervisory line 332, back contact and a 2 1m ature 445, armature 443 and its baclrcon tact, armature 447 and its front contact, armature 448 and its baclrcontactfi conductor 449'.

contact' otthe selecting through the fourth relay 511, at the substation conductor 450,

through the winding of the check relay 412 at contact, conductor 452 through the third contact of the selecting relay 511 at the substation and through battery to ground.

It will be recalled that the check circuit traced for the first associated pair of selecting relays at the office and substation, was completed from battery at the oifice to ground at the substation over the supervisory line. lhis check circuit, it will be noted, in turn, while being completed over the same supervisory line as the first check circuit was, is

completed from ground at the ofiice, to battery at the substation. In a similar manner,

each of the remainin pair of associated selecting relays is chec ed by an-impulse individual to that particular pair of selecting rela s in the group.

pon energization of the check relay 319 at the office, the relay 320 is energized over i the circuit traced. above which in turn energizes the relay 321. The energization of the relay 321 transfers the control'and supervisory lines through to their operating point "the substation. In a similar manner, e0 first four drive impulses are completed from and at the same time deenerglzes the check relay 319, thishaving all been described in detail above.

As a result of the energization of the check relay 412, at the ofiice, an energizing circuit is completed for the relay 411 which, in turn, completes an energizing circuit for the relay 410 in a manner which has already been described in detail above. The energization of the relay 410 transfers the control and supervisory lines through to the operating point and at the 'sametime energizes the relay 413 which, in turn, deenergizes the check relay.

412 as was described in detail above.

' The drive line is now opened in the manner described above, the relay 318 being energized over the contact of thesucceedmg selecting relay stop key. When the swltchover relay 201 is energized, it not only opens the energizing circuit of relay 211 and transfers the circuit from the drive relay to the succeeding selecting relay 212, but it also opens the energizing circuit for relay 200 which thereupon deenergizes. The same operations take it will be noted t at not only are the selecting relays successively deener ed but the switchover relays are also eenergized and only one selecting and switchover relay is Energizedsimultaneoirsly for any length of uric. i It will be noted that thefirst t'wo drive impulses thus far traced have both been completed from battery at the oifice to ground at battery at the ofice to ground at the substation. en, however," the fourth selecting relay has been energized and deenergized and the switchover rela 203 is energized, a circuit is completed for t e relay 315 from ground lace at the substation. Thus the em sult of the energization of the relay 315, thedrive circuit is transferred from the negative side of battery to the positive side over the armature 345 and its front contact as distinguished from its original circuit to the negative side of battery over armature 345 and its back contact. v

At the sub-station, upon the completion of the fourth selecting operation the relay 415 is energized over a circuit from ground through battery, through the winding of the relay 415, the front contact and armature 550, conductor 521, to ground over the armature 432 and its back contact. The drive circuit is thus transferred from the ground connection over armature 444 and its back contact to the negative side of battery over armature 444 and its front contact.

It will be noted from the drawings that the relay 315 is energized in multiple over the front contact and armatures of the relays 203, 204, 205 and 206, while at the substation the relay 415 is energized in multiple over the front contacts of relays 503, 504, 505 and 506. Thus, during the next four drive impulses and until the end of the eighth drive impulse the current over the drive line is reversed in polarity from that described in detail above. During this period the four checking impulses transferred during the first group of drive impulsesare repeated. Since the po larity of the drive impulse is different, however, the combination of impulses for this group'of selecting relays is different, from that for the first group.

It will be noted also that the drive impulses thus far described have been transmit ted over the conductor 351 and over the back contact and armature of 350, while the chebking impulses have been transmitted over the conductor 362 over the back contact and ar mature 373. Following the .energization of the eighth selecting relay and the ei hth switchover relay just before the ninth se ecting 0 ration, an energizing circuit is comlete for the relay323 from ground through attery, the winding of the relay 323, through the front contact and armature 243 over cone ductor 342 to ground, through front contact and armature 337 As a result of the energization of the relay 323, the drive line is now completed over armature 350 and its front contact, to conductor 362 instead of conductor 351, while the former drive line 10 'ng conductor 351 now functions as a c aching line completed over armature 373 and its front contact. I Simultaneously, at the substation, following energization of the eighth selecting relay and the eighth switchover relay, an energizing circuit is completed for the relay 408 y i ceeding from ground toba'ttery through the winding of the relay 408 and through the front contact and armature 540 to ground over conductor, 521 byway of back contact and'armature 432. The energization of relay 408 switches the conductors 362 and 351 in a manner already described in connection with the operation at the ofiice. Conductor 362 which formerly functioned as a supervisory conductor now operates as a drive line completed over the, front contact and armature 434, while the conductor 351 formerly functioning as a drive wire now transmits supervisory signals over the front contact and armature 445. It will be noted that the relay 323 is energized in multiple over the front contact of the eighth and ninth switchover relays 207 and 208, while at the substation the relay 408 is energized in multiple over the front contact of the switchover relays 507 and 508. In this manner the ninth and-tenth operating impulses are transmitted as drive impulses over the conductor 362 and supervisory impulses are transmitted at this time over the conductor 351. a

In Figure 7 the manner in which the suc- (group of selecting relays at the ofiice 1s starte Figure 3 is shown in a diagrammatic manner. As will be clear from the above description, when the switch-over relay 209 is energized, a

circuit is prepared for the first selecting relay 710 of the second group, and later completed this can be carried further by performing.

' same combinations of selecting position.

second selcctin over the front contact of armature 348. When the next. succeeding impulseis received and relay 314 is energized, selecting relay 710' is energized. The. first selecting relay at the substation is energized simultaneously with the relay 710. From this point on, the operation of the second group is identical with that of the first group, the only distinctions being in the absence of a dummy selecting position in the second up. The code which operates selecting relay 710, is the same. as that which operates relay 210. The relay will be operatedby the same code as that which operated relay 211, and'etc.

It is evident, of course, that the switching over thus described can be repeated in the manner described for reversing the functions of the supervisory and control lines, and that a further switchover operation for reversing the-functions of the-drive and control wires,

etc. In this manner, a large number of variations can he obtained without repeatlng-the impulses at any one it has been assumed for the present illus tration, that the dispatcher desires to close the breaker associated with the firstseleeting "innit. In order to perform a close operation,

I 'QQ'the dispatcher will openthe stop key individual to the first selecting position.

into operation by the apparatus in" nsoaaoa Upon o eration of the stop key associated with the rst selecting position, the energizing circuit for the relay 315 formerly traced over the stop key is not completed when the first selecting position is reached and the drive circuit remains closed. The first selectvidual closing Iey 112, the right hand contact of stop key 105, the conductor 165, the sixth contact of. the selecting relay 210, conductor 271, through the contacts of the master key 139, conductor 272, armature 381, and its front contact, the back contact and armature 382 and the front contact and armature 348 to ground. This circuit, it will be noted, is completed over the front contacts and annatures of relays which'are energized only if the correct check circuitwas completed, thus adding additional guardto the accuracy of the selecting operation;

As a result of the energization of the relay 303 which is energized in response to the operation of the individual key to its closed position, as distinguished from-the energize.- tionof the trip relay 305 when the individual operating key is operated to its trip position, an energizing circuit is completed for the slow release relay 302 from ground through battery through the winding of the relay 302 over the back contact and armature 383, the front contact and armature 384, the armature 381 and its front contact, the back contact and'armature 382 and the front contact and armature 348 to ground.

As a result of the energization of the re- .lay 302, the first impulse for the operating control code is completed for energizing the relay 306 at the ofice. This circuit is completed from ground through battery, the back contact and armature 385, through the winding of the relay 306, the front contact and armature 386, the front contact and armature 361, front contact and armature 344, armatime 373 and its back contact, conductor 362, back contact and armature 445, armature 446 v and itsback contact, armature 447 and its front contact, armature 448 and its front contact, armature 482 and its back contact, con- 'ductor 556 through the sixth contact of the selecting relay 510, conductor 557, and armature 631 and its front contact to ground.

At the substation, an energizingiiircuit is completed for the relay .400 from ground through battery over the-back contact and armature 484 through the winding of the relay 400, the conductor 460, through the last rec contact of the selecting relay 510, conductor 565, the front contact and armature 486, the front contact and armature 428, the control line 335, armature 362 and its front contact, armature 391 and its front contact through the last contact of-the selecting relay 210, the contacts 1400f the master control key, armature 385 and its back contact, back contact and armature 388, conductor 286, the closed right hand contact of the stop ke 104, conductor 160, and through the' fi h' contact of the selecting relay 210 to ground.

As a result of the energization of the relay 400 at the office, an energizing circuit is com: pleted forthe slow release relay 407 from ground to battery, winding of the relay 407, the front contact and armature 487 front contact and armature 480, front contact and armature 438, and the front contact and armature 437 to ground. The energization of ;relay 407 completes an energizing circuit for the rela 402 from ground through battery throug the winding of rela 402, the back contact and armature 488, ront contact and armature 489, front contact and armature490, the front contact and armature 480, front contact and armature 438, and front contact and armature 437 to ground. As a result of the energization of relay 402,

a locking circuit is completed therefor, from ground to batter through the winding of the relay 402, the 491, the back contact and armature 492, the front contact and armature 490 to round over the circuit traced above. A urther result of the energization of relay 402, is to I prepare an energizing circuit for the relay 401 at armature 492 and its front contact, but this circuit is not completed at this time for the reason that the armature 489 is in engagement with'its front contact.

. At the ofice, the energization of the relay 306 com relay 30%, from ground t rough battery, winding of the relay 307, the back contact and armature 392, front contact and armature. 393, front contact and armature 384, armature 381 and its front contact, back contact and armature 382, and the front contact and armature 348 to ground. As a result of the energization of the relay 307, a locking circuit is completed for this relay from 'ground to battery, the front contact and armature 394, the front contact and armature 384, and armatures 381 and 382 to ground over the armature 348 over the circuit traced above.

A further result of the energization of the relay 307 is to open the circuit for the relay 400 originally traced over the armature 388. The relay 400, is, as a result, d eenergized.

Upon the deenergization of the relay 400, an-

energizing circuit is completed for the relay 401 from ground through battery, through the ont contact and armature etes an energizin circuit for the' winding of the relay 401, over the back contact and armature 493, front contact and armature 492, and over. the back contact and armature 489 to ground over the front contact and armature 480 over the circuit traced above. Following energization of the relay 407, an energizing circuit is completed for relay 406 from ground through battery,

winding of relay 406, front contact of the first armature or relay 407, back contact and armature 487, front contact and armature 480, front contact and armature 438, and front contact and-armature 437 to ground.

3 The energization of the relay 401 completes a lockin circuit for itself from ground through attery through the winding of the relay 401, and the front contact and armature 473 to groundover the front contact and armature 490 traced above. A further result of the energization of relay 401 is to open an additional point in the circuit of the relay 400 at armature 484 which now enga es its front contact and to prepare a circuit or the relay 403 at the front contact and armature 488, which however, is not completed this time by reason of the fact that the armature 489 is in engagement with its back contact.

The energization of the relay 401, at the substation, also opens the'energizing circuit for the relay 306 at armature 484, which is now in engagement with its front contact. The first t'wo operation control code impulses are thus completed. Upon the deenergization I of the relay 306, an ener zing circuit is comleted for the relay 309 f r om ground through attery, through. the winding of the relay 309, back contact and armature 398, back con-. tact and armature 397, to ground over the frgont contact and armature 394 as'traced a ove.

It will be noted from the circuits traced thus far, that the first operation for transmitting a code to close the circuit breaker, com: prises transmitting an impulse from a battery of negative polarity at theoffice over pair of relays mentioned .above at the other station. That is, the local relay energized at the ofiice, opens the circuit for the relay at the substation which was energized over the line connecting the stations, whereas the local relay energized at the substation, opens the ener izing circuit of the relay energized at the o co over a line connecting the stations. The first two relays are now again energized, but this time with energy of reverse polarity. By this arrangement, unless the correct impulse has been completely received o relays in synchronism. In the particular arrangement disclosed, this is applied for operation control although it will be understood that the" synchronous operation can be applied for any desired purpose such as an ervisory control selection of units point by pomt. The next impulse transmitted between the stations is now completed from the ground at the ofiice over armature 348, its front con- .back contact, the front contact and armature 385 through the winding of the relay 306 and ever the circuit traced above including the supervisory line to the substation, and over the circuit traced above at the substation, including armature 448 and its front contact,

the armature 482 and-its front contact, the

back contact and armature 494, the back contact and armature 495, the front contact and armature 496, the front contact and armature 475, the front contact and armature 498, to battery and ground.

Similarly, therelay 400 has now a circuit completed from ground over the armature 437 and its front contact, the armature 438 and its front-contact, armature 480 audits front contact, the front'contact and armatur 484 through th'e\winding' of the relay 400 over the circuit traced above over the control line thecircuit traced above, to the armature 387 and its front contact, instead of. the back contact as traced above and over the back contact and armature 399 to battery and ground.

As a result of the energization of the relay 306 at the other), and the relay 400 at the sub station, ,a'second time as a result of the transmission of the third and fourth code impulses, the-relay 310 at the ofice is energized over the front contact of armature 392 and thefront contact and armature 393, over the. same circuit as traced above for the relay 30?. The energization of the relay 310 opens the circuit for the relay400 at arma- 5 circuit as. traced'above for the relay 401. r'

"ture 399, causing this relay to deenergize The energization of the relay 400 at the remote station a second time completes an energizing circuit for the relay 403, over the back contact and armature 497, the front contact and armature 488 and front contact and armature489 and thereafter over'a similar circuit traced for the relay 401 above. The

energization of the "relay 403 completes a locking circuit or itself over armature 499 and prepares'an energizing circuit for the relay 404. Upon the deenergization of the relay 400as'described above, an energizing circuit iscompleted-for the relay 404voyer the fronkeontactoiarmatures 493, 492, and the back contact-of armature 489 over the see and armature 37 6 to ha tions are transmitted from the first to the second stations.v Although any combination of code impulses can be transmitted, for purposes of illustration only, as illustrating the preferred modification, threefimpulses aretransmitted for performing a trip operation and five-impulses are transmitted for performing a closin operation; tact and armature 381, armature 396 and its gizing circuit for the relay 302 at armature 383. As a result of they deenergization of the relay 302, the energizing circuit for the relay 306 which'ijspre ared atth s time over the front eonta'ct'o :armature 386 is now opened and this relay remains. deenergi'zed. Relay 400 on theother hand continuesenergized during the operation of the fourth and fifth relays 310 and 311 at the ofiiee, the, 011'- cuit therefor being co tact and amnatm'e 39 through battery to ground as traced abo e when the relay 310 is deenergized and 0%:rthefront contact e and ground when the relay 311 is energize d. As a result of the relay'400 remaining energized for more than the usual signalling-period, the relay 406, whose energizing circuit it will be recalled, .was traced over the back contact of armature 487, becomes deenergized by reason while armature 48 is in engagement wit its front contact. a

After a period of time this relay deenergizes and an operating circuit for performof the length of eriod its circuit is 0' en,

erforming the so I as pleted over back conice ing the closingoeration is completed from ground through attery over'the armature .498'an'd itfsfront contact, the armature 475 and its front contact, armature 496 and its back contact, armature 590 and its front'contact, and over the conductor 598 through the seventh contact of the selecting relay 510g conductor 598, and through the winding the relay 612 to ground. As a result of tfhe energization of the relay 312, an obv ous energizing circuitis completed for, the sole are noid 614 which in turn completes an obvio energizing-circuit for the operating magnet 615 to operate the circuit. breaker 61 fm its tripped ton to its cl ositmn. this circuit 113:: had been used a it had been desired to trip the circuit as it would merely have n ryto-moive the hey its, trip in 

